Solve (5x-1)² > 0: Finding Positive Values of a Quadratic Function

Quadratic Inequalities with Perfect Squares

Look at the function below:

y=(5x1)2 y=\left(5x-1\right)^2

Then determine for which values of x x the following is true:

f(x)>0 f(x) > 0

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Look at the function below:

y=(5x1)2 y=\left(5x-1\right)^2

Then determine for which values of x x the following is true:

f(x)>0 f(x) > 0

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Recognize that any square of a real number is greater than zero unless the number itself is zero.
  • Step 2: Find when the expression 5x1 5x - 1 equals zero, since the square is zero only at this point.
  • Step 3: Exclude this value to determine when the quadratic is strictly greater than zero.

Let's work through each step:
Step 1: The expression given is y=(5x1)2 y = (5x - 1)^2 . We know that the square of any non-zero real number is positive.
Step 2: Set the inner expression to zero to find the critical point:
5x1=0 5x - 1 = 0
Solving for x x , we add 1 to both sides:
5x=1 5x = 1
Divide both sides by 5:
x=15 x = \frac{1}{5}
Step 3: Therefore, (5x1)2>0 (5x - 1)^2 > 0 for all x15 x \neq \frac{1}{5} .
This means that the quadratic expression is greater than zero for all real values of x x except x=15 x = \frac{1}{5} .

Thus, the solution to the problem is x15 x\ne\frac{1}{5} .

3

Final Answer

x15 x\ne\frac{1}{5}

Key Points to Remember

Essential concepts to master this topic
  • Perfect Square Rule: Any squared expression is positive except when base equals zero
  • Zero Point Method: Set 5x - 1 = 0, solve to get x = 1/5
  • Verification: Check any other value like x = 0: (5(0) - 1)² = 1 > 0 ✓

Common Mistakes

Avoid these frequent errors
  • Thinking the inequality has no solution
    Don't assume (5x - 1)² > 0 has no solutions = missing almost all x-values! Students think 'greater than zero' means impossible since squares can be zero. Always remember that squares are positive everywhere except at their zero point.

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below intersects the X-axis at points A and B.

The vertex of the parabola is marked at point C.

Find all values of \( x \) where \( f\left(x\right) > 0 \).

AAABBBCCCX

FAQ

Everything you need to know about this question

Why isn't the answer 'all values of x'?

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Because at x=15 x = \frac{1}{5} , the expression equals zero, not greater than zero. We need strictly greater than, so we must exclude this one point.

How do I find where the expression equals zero?

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Set the inside of the square equal to zero: 5x1=0 5x - 1 = 0 . Solve by adding 1 to get 5x=1 5x = 1 , then divide by 5 to get x=15 x = \frac{1}{5} .

What does the 'not equal' symbol mean?

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The symbol \ne means 'not equal to'. So x15 x \ne \frac{1}{5} means x can be any real number except one-fifth.

Can I test values to check my answer?

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Absolutely! Try x = 0: (5(0)1)2=(1)2=1>0 (5(0) - 1)^2 = (-1)^2 = 1 > 0 ✓. Try x = 1: (5(1)1)2=42=16>0 (5(1) - 1)^2 = 4^2 = 16 > 0 ✓. But at x=15 x = \frac{1}{5} : (5151)2=0 (5 \cdot \frac{1}{5} - 1)^2 = 0 , which is not > 0.

Is this the same as solving a quadratic equation?

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Not quite! We're solving a quadratic inequality, not an equation. Instead of finding where it equals zero, we're finding where it's greater than zero.

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